Latch for doors



A ril m, 1950 H. E. D. BAKER 2,503,315

LATCH FOR DOORS Filed July 25, 1948 2 Sheets-Sheet l FIGJ x 2 5 IO 4 l2 l3 3 7 l4 [5 IO 3 7 April H, 1950 H. E. D. BAKER 2,503,315

' LATCH FOR DOORS Filed July 23, 1948 v 2 Sheets-Sheet 2 C 6 F/G.//. FIG/3 y lo o n. o 1 o W 7 3 9 a H 4- I FIG. 5.- O 0 j 7 l r o o I l3 7 l5 a 6 FIG/4 /-'/4 9 8 5 P V FIG/6J1? la/wfld Lneofqem fiakw A; Mam

Patented Apr. 11, 1950 LATCH FOR DOORS Harold'Ernest Dean Baker, Stourbridge, England Application July 23, 1948, Serial No. 40,267

In Great Britain November 11, 1947 7 Claims. 1

This invention relates to door latches of the kind comprising a bolt which is projected from a body or housing by spring loading and is adapted to be withdrawn into said body or housing and against the spring loading by a rotary cam or follower operated by a handle or knob.

The primary object of the present invention is to provide a new or improved construction of door latch of the kind referred to which will ensure that the bolt has a particularly smooth action and yet is free from lateral movement or play when in its operative or shot position.

According to the invention, the latch bolt is tapered, the convergence of its relatively inclined faces being toward the leading or forward end, and the latch housing is provided with correspondingly convergent bearing faces with which said inclined faces on the bolt co-operate when the latter is maintained in its operative or shot position by the spring-loading. Preferably the taper of the latch bolt is symmetrical with respect to its longitudinal axis and is such that the cross section of the bolt decreases progressively in both its width and thickness dimensions towardsthe leading or forward end. Thus when the bolt is maintained in its operative or shot position, the co-operation of the inclined faces on the bolt with the confronting and correspondingly inclined bearing faces in the latch housing serves to prevent lateral displacement or side play, whilst immediately the bolt commences to be withdrawn against the spring loading said cooperating faces are disengaged. The relatively inclined bearing surfaces for the bolt preferably extend throughout the length of the latch housing and the bolt is tapered over its full length.

According to a further feature'of the invention the spring loading of the latch boltis afforded by a helical compression spring operating directly between said bolt and the rotary, cam or follower whereby the bolt is adapted to be withdrawn against the action of said spring.

Preferably a rotary locking. device is provided for retaining the bolt in either of its extreme positions as desired.

In order that the invention may beclearly understood, it will now be more fully described with reference to the embodiment shown, by way.

of example, in the accompanying drawings wherein:

Fig. 1 is a side elevation of the latch with the cover plate removed toshow the mechanism, the bolt being in its normal or shot position.

Fig. 2Jis an end elevation of Fig. 1. I

Fig. 3 is a similar view to Fig. 1 butshowing the bolt in its withdrawn position.

Figs. 4, 5 and 6 are respectively a side elevation, end elevation and an opposite side elevation of the latch bolt.

Figs. 7 and 8 are sectional end elevations taken on the lines A. B. and'C'. D. respectively in Fig. 6.

Fig. 9 is a sectionalv plan taken on the longi tudinal centre line of Fig. 6.

Figs, 10, 11 and 12 are respectively a side eie vation, an end elevation and a sectional plan of the latch body, the section being taken on the longitudinal centre line of Fig. 10.

Figs. 13m) and (b) are opposed side elevations of the cam or follower andFig. is a plan thereof.

Figs. 14(a) and (b) are respectively side and end elevations of the rotary locking device.

Fig. 15 is a perspective view of a combined bearing-slipper and guide for that end of thelatch' spring which engages the cam or follower.

Fig. 16 is an elevation of the helical latch spring in its unstressed state.

Referring to the'drawings, l is the latch body or housing, .2 is the latch bolt, .3 is the rotary cam or follower, 4 is the loading spring and'5 is the rotary locking device. 1

The latch bolt 2'has a rectangular cross section and decreases progressively in both width and thickness toward the leading or forwardend which is curved on its forward face, the taper being symmetrical with respect to the longitudinal axis of the bolt.

A through longitudinal passageway which has the same cross section and taper as the bolt, so as to aiford'therefor full lengthinclined bearing surfaces, is afforded between the body I and a cover plate and extends from a rectangular opening in the end plate portion 6 at the forward end of the body I to the rear end of thelatter; said passageway being defined by the inclined and confronting inner faces of the body side plate portion and the cover plate I and by the opposed inclined inner faces of flanges! formed integrally with the body I.

Axially aligned bearing holes for the rotary cam or follower 3 are formed at 8 in the opposed side walls of the latch housing toward its rear end, the common transverse axis of said bearing holes intersecting the longitudinal axis or centre line of the passageway through the housing. Other axially aligned bearing holes are formed at 9 in the opposed side walls of the housing toward its forward end for the rotary locking device 5, the common transverse axis of these further bearing holes also being on the longitudinal axis or centre line of the passageway through the housing.

The latch bolt, 2 is formed with two through slots [0, ll respectively the slot lil being for the rotary cam or follower 3 and the slot ll being provided for the rotary locking device 5.

The rotary cam or follower 3-see particularly Figs. 13(a), (b) and (c)-is in the form of a barrel which is mounted for rotation in the bearing holes 8 and is accommodat'edin the slot ID in the latch bolt 2. The barrel of the cam or follower 3 is formed integrally with acam piece 3 having a forwardly facing semi-cylindrical surface which is concentric with but of larger radius than the barrel, and diametrically opposed rear ingly disposed rear end faces of recesses l2 which accommodate the laterally projecting extremities of the cam piece 3 Also formed integrally with the barrel of the cam or follower 3 and centrally in relation to its cam piece 3 is a radially and forwardly projecting stop piece 3 having relatively inclined tangential side faces one or other of which, according to the direction of rotation of the cam or follower 3, will co-operate with the adjacent side face ofthe slot ID to determine such rotation. The axial bore through the barrel of the cam or follower 3 is of square cross section to receive the usual rod, of corresponding section, associatedwith the operating knobs or lever handles (not shown).

' The length of the slot l and of the lateral recesses I2 is such as to permit the requisite range of movement of the latch bolt. I v

The slot ID has a central and'forwardly directed extension Ill the forward closed end of which affords an abutment for one end of the helical compression spring 4 which is accommodated in and located by said slot extension Hl and has its other or rear end embraced by a U- shaped slipper l3. The'limbs of this slipper l3 are guided by the walls of the slot extension Ill and its closed end or connecting piece is maintained in engagement with the semi-cylindrical surface of the cam piece 3 of the cam or follower 3 by the action of the spring 6 so that the latter operates to urge the latch bolt'2 forwardly.

The rotary locking device is alsoin the form of a barrel with a through axial bore of square cross-section which receives a rod, of corresponding section, associated with an operating knob or lever'handle, and the barrel is formed integrally with diametrically opposed arms with common tangential side faces and arcuate end faces. The barrel has axially'aligned bearing trunnions 5 which engage within the bearing holes 9 and at the root of one of these trunnions is formed a square part 5 for engagement by a springy wire I for retaining the rotary locking device in either of its two positions as hereinafter described.

The slot II has a parallel-sided forward portion of slightly greater width than the diameter of the barrel of the rotary lockingdevice, and a rear part-circular portion of slightly greater radius than that of the arcuate ends of the arms of the rotary locking device, these parts of the slot being connected at one side by an abutment face or shoulder ll for determining the rotary movement of the locking device.

With the parts in the positions shown in Fig. 1 the bolt is maintained in the forward or shot position by the loading spring 4, the diametrically opposed rear faces of the cam piece 3 of the cam or follower 3 are engaged flat against the rear end faces of the recesses l2, and the rotary locking. device 5 has its arms in line with the forward part of the slot I l and is retained in that position by the springy wire I4. In this latter connection the wire M has a looped rear end anchored in a correspondingly shaped recess at IS in one of the flanges 1 and its forward off-set end engages the adjacent side face of the square part 5 on the 'rotary locking device to retain the latter in its longitudinally aligned position.

In order to withdraw the latch bolt to the position shown in Fig. 3 the cam or follower is rotated by its associated knob or handle and associated operating rod (not shown) until one or other side of the stop piece 3 engages the adjacent side of the slot [0. During this rotary movement the outer end of one or other of the diametrically opposed rear faces of the cam piece 3 (according to the direction of rotation) cooperates with and rides over the rear end face of the adjacent recess l2 so as to move the latch bolt 2 rearwardly against the spring loading. At the end of the withdrawal movement the semicylindrical surface of the cam piece 3 is engaged by complementary arcuate faces ll! at the forward ends of the recesses I2 and the rotary looking device 5 is in the forward part of the slot I I. If the latch operating knob or lever is released the spring 4 comes into action to return the bolt 2 to its fully shot position and return the cam follower 3 to its normal position through the co-operation of the rear end faces of the recesses l2 with the cam piece 3*. In this conneotion the latch bolt 2 is formed at 2 with a clearance recess so that the springy wire M cannot interfere with the withdrawal and shooting of said bolt.

If it is desired to prevent withdrawal of the latch bolt from the shot position (Fig. 1) the rotary locking device is turned by its knob or handle in a clockwise direction within the partcircular rear end of the slot H until its arms are disposed at right-angles to the longitudinal axis of the bolt and one of said arms engages the abutment face or shoulder ll". During this rotary movement a corner of the square part 5 forces away the forwardly directed end of the springy wire M which then returns to co-operate with another face of said square parts 5 and retain the rotary locking device in the locking position. To free the bolt 2 for operation the rotary locking device is turned back, i. e. anticlockwise, until the arms thereof are aligned longitudinally with the forward part of the slot ll. Thus'the wire 14 gives a snap or spring click action which indicates to the operator the passing of the locking device from one position to the other.

.By providing a taper bolt operating in a correspondingly tapered housing as above described, not onlyis the bolt held against lateral movement or rattle by the full-length co-operation of the inclined faceswhen the bolt is in its operative or shot position, but also the bolt has a particularly smooth action since said (So-operating inclined faces separate immediately the bolt commences its withdrawal movement, so that friction is reduced and bolt floats under the control of the loading spring and the rotary cam or follower. Another advantage of the construction is that the taper bolt and the housing with the taper passageway can conveniently be produced as die-castings in aluminium or other appropriate metal or alloy or other material.

I claim:

1. A door latch comprising in combination a latch bolt, a latch housing for the latch bolt, spring-loading means urging the latch bolt into an operative position, in which the leading end of the bolt projects from said housing, and a rotary member for withdrawing the latch bolt against the spring-loading, characterised in that the latch bolt is tapered, the convergence of its relatively inclined sides being toward the leading end, and in that the latch housing has correspondingly convergent bearing faces with which said inclined faces on the latch bolt co-operate when the latter is maintained in its operative position by the spring-loading.

2. A door latch comprising in combination a tapered latch bolt, the taper being symmetrical with respect to the longitudinal axis and such that the cross section of the latch bolt decreases progressively in both its width and thickness dimensions toward the leading end, a latch housing having correspondingly convergent bearing surfaces for the latch bolt, spring-loading means urging the latch bolt into an operative position, in which its inclined sides co-operate with the inclined bearing surfaces of the latch housing and the leading end of the latch bolt projects from said housing, and a cam member mounted for rotation in the housing and adapted to co-operate with the latch bolt for withdrawing it against the action of the spring-loading.

3. A door latch as claimed in claim 2, wherein the relatively inclined bearing surfaces for the latch bolt extend throughout the length of the latch housing and the latch bolt is tapered over its full length.

4. A door latch as claimed in claim 2, wherein the spring-loading means comprises a helical compression spring accommodated in a slot in faceone of the opposite ends of which, according to the direction of rotation, co-operates with an opposed abutment face on the latch bolt so as to move the latter against the spring-loading which is afforded by a helical compression spring operating between the part-cylindrical surface of the said cam piece and the forward end of a slot in the latch bolt, which slot accommodates saidspring and permits the full range of movemerit of the latch bolt relatively to the rotary 1 cam member.

6. A door latch as claimed in claim 2, wherein the spring-loading means comprises a helical compression spring accommodated in a slot in the latch bolt and operates between a part cylindrical concentric surface of a cam piece on the rotary cam member and that end of said slot which is nearer the leading end of the latch bolt, said slot being formed contiguously with lateral recesses into which the opposite ends of said cam piece project and the rear ends of which afford abutment surfaces with which, according to the direction of rotation, the ends of said cam piece co-operate to move the latch bolt against the action of the helical compression spring.

7. A door latch as claimed in claim 2, wherein the spring-loading means comprises a helical compression spring accommodated in a slot in the latch bolt and operating between a concentric surface on the rotary cam member and that end of said slot which is nearer the leading end of the latch bolt, and in which said rotary cam member has a. stop piece which'co-operates with one of the sides of the slot, according to the direction of rotation, to determine the withdrawal of the latch bolt.

HAROLD ERNEST DEAN BAKER.

No references cited. 

